1. Field of the Invention
This invention generally relates to a thermal printer for carrying out printing thermally by using a thermal printhead and in particular to a dual mode thermal printer having a multi-color recording mode and a monochromatic recording mode.
2. Description of the Prior Art
A thermal printer is well known in the art. Typically, use is made of thermally sensitive paper as a recording medium, which is moved relative to and in contact with a thermal printhead provided with a plurality of heat-producing elements, such as electrical resistors, arranged in the form of a single array as spaced apart from one another at a predetermined pitch. Recently, there has been developed multi-color thermally sensitive paper capable of producing two or more color dots when heated. Such multi-color thermally sensitive paper is typically comprised of a plurality of layers overlying one on top of another, each capable of producing a predetermined color when it is heated to within a predetermined temperature range. In such a multi-color thermal printer, it is important to properly control the temperature of the thermal printhead, in particular each of its resistor elements, so as to obtain a printed image high in quality. However, in order to carry out a proper temperature control operation, the recording speed must be set at a lower level, which is disadvantageous.